Fire-Retardant Current Collector Structure for Lightweight Li-Ion Cells
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Solution Overview
Problem
Conventional lithium-ion battery systems face limitations in energy capacity, mechanical stability, and safety due to the lack of lightweight and robust current collector devices, which can lead to thermal runaway, fires, and explosions.
Innovation Solution
A current collector device composed of a polyimide (PI) core layer embedded with triphenyl phosphate (TPP) flame retardant and coated with ultrathin metallic layers to provide fire-extinguishing properties, maintaining electrical conductivity and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current collector devices are used, then mechanical stability is maintained, but weight is excessive and fire safety is poor
Solution Approach 1:
The patent employs a composite structure consisting of a polyimide core layer containing phosphate fire retardant combined with ultralight metallic foil layers (copper or aluminum). This composite material approach enables the current collector to achieve both reduced weight and enhanced fire safety simultaneously, as the polyimide provides fire resistance while the thin metallic layers provide conductivity with minimal weight addition.
Solution Approach 2:
The patent changes the material parameters by replacing conventional heavy metal foils with ultralight metallic layers at thickness of 500 nm, and incorporates phosphate fire retardant into the polyimide matrix. These parameter changes in material composition and thickness enable both weight reduction and fire safety improvement.
2Use of energy by moving object
If conventional current collector devices are used, then structural integrity is maintained, but specific energy capacity is limited
Solution Approach 1:
The composite structure of ultralight metallic foil (500 nm thickness) combined with polyimide core layer achieves optimal balance between weight and energy capacity. The minimal metallic layer weight allows higher specific energy capacity while maintaining necessary electrical conductivity and mechanical integrity.
Solution Approach 2:
The patent uses ultrathin metallic foil layers at 500 nm thickness as flexible conductive layers, which minimize weight while maintaining electrical functionality. This thin film approach directly contributes to increased specific energy capacity by reducing the weight denominator in the specific energy calculation.
3Reliability
If fire retardant materials are added to the current collector, then fire safety is improved, but device complexity increases
Solution Approach 1:
The patent merges the fire retardant function directly into the polyimide core layer by incorporating phosphate fire retardant during polymerization. This integration eliminates the need for separate fire retardant layers or components, thereby improving fire safety without significantly increasing device complexity.
Solution Approach 2:
The polyimide core layer serves multiple functions simultaneously: it provides the structural backbone of the current collector, incorporates fire retardant properties through phosphate addition, and supports the ultralight metallic foil layers. This multi-functionality reduces overall device complexity while achieving fire safety goals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves a significant increase in specific energy and safety by minimizing dead weight, allowing for fast and efficient self-extinguishing of battery fires while maintaining normal cell operation.
Implementation Method 1
rapid self-extinguishing properties, reducing the risk of thermal runaway and fire
Implementation Method 2
a first substantially planar metallic layer including a foil material... a second substantially planar metallic layer including the foil material
Data Source
AI summary
Example implementations include a current collector device with a first substantially planar metallic layer including a foil material, and a core layer including a polymer and phosphate fire retardant and disposed by a first planar surface thereof on a first planar surface of the first metallic layer. Example implementations also include a method of manufacturing a core layer for a current collector device, by combining benzene and oxy dianiline at a first ratio in a solvent to form a solution, adding dianhydride to the solution at a second ratio, adding triphenyl phosphate to the solution, polymerizing the solution by heating the solution to form a polymerized solution; and forming a polymer film from the polymerized solution. Example implementations also include a temperature modulating layer including a temperature modulating material and disposed by a first planar surface thereof on a second planar surface of the first core layer.